1. Technical Field
The present invention relates to a control apparatus and the like controlling ejection of a pulsed liquid jet by controlling a drive voltage waveform applied to a piezoelectric element.
2. Related Art
There is a technique of cutting a cutting target object by ejecting a liquid in a pulse form. The liquid ejected in a pulse form is a liquid jet flow which is ejected from a nozzle in a pulsating manner, and is referred to as a “pulsed liquid jet” as appropriate in the present specification.
A pulsed liquid jet may be variously applied, and, for example, JP-A-2005-152127 has proposed a technique in which the pulsed liquid jet is used for surgery in a medical field. In this case, a cutting target object is living tissue, and a liquid is physiological saline.
As one of the mechanisms generating a pulsed liquid jet, there is a mechanism using a piezoelectric element. The mechanism applies a pulsed drive voltage to a piezoelectric element so that the piezoelectric element generates instantaneous pressure in a working fluid (fluid), and thus ejects the liquid in a pulse form. Thus, the strength of the pulsed liquid jet is changed by controlling a drive voltage applied to the piezoelectric element. JP-A-2009-39384 or JP-A-2011-36533 discloses a technique of changing a characteristic value of a drive voltage applied to a piezoelectric element, for example, the amplitude or a frequency of a drive voltage waveform.
A cut depth or a cut volume related to one pulsed liquid jet can be changed by changing a drive voltage. However, in a case of taking into consideration convenience or usability when cutting is performed by using a pulsed liquid jet, simply changing a cut depth or a cut volume cannot be said to cope with all cutting applications and thus to be versatile. For example, there is a need for changing an aspect during cutting (hereinafter, referred to as a “cutting aspect” as appropriate), such as a need for “narrow and deep” cutting, or a need for “wide and shallow” cutting.